Couple of questions about shortening, lye and soapcalc


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Apr 29, 2008
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I have a tub of shortening, it's a thick, opaque, white sort of goop. Not crisco brand, its the store brand. Where would I find that or the equivalent on the list on soapcalc? There's no shortening there. I have no other use for this in my kitchen, I'd like to use it in some soap.

What is the difference between crisco in the tub and the liquid crisco in the bottle?

2nd question, when you're calculating on the soapcalc, and it says to use, for example, 3.118 of lye and 7.98 of water, how do you measure that? My scale doesn't have figures like 3.118 7.98, my scale only has 2 digits for ounces so I would measure that as 3.1 ounces of lye and 7.9 of water. Is that wrong?

Just wanted to clear that up. I've made 6 not so good batches of soap, and finally (so far so good) one batch that came out great, so I'm thinking my measuring is correct. I think know some of my mistakes in the past: everyting was too hot, too much FO, not covering the soap good enough during sap, ect.

I'm expecting some oils in the mail today and plan on going crazy with them all tonight!


According to Karen Miller's site, shortening has a SAP of 136. Dr. McDaniel's book says it's 137. Nerius has it as 136, so let's go with 136. All you need to do to get correct lye calculations is to find another fat with a SAP of 136. Both Miller and Nerius say that almond sweet, corn, peanut and safflower have a SAP of 136. (Funny, McDaniel has them all as 137.)

SAP values vary depending on which source you use not only for the values but for the oils themselves, so I checked SoapCalc's values for almond sweet, corn, peanut and safflower and discovered that all the values except safflower are just a bit off from Miller and Nerius, so you should enter your shortening as safflower oil.

Note that the fatty acid lineup for shortening is unlikely to be the same as safflower oil so all your qualities will be thrown off: hardness, cleansing, smooth, bubbly, all that stuff will have incorrect amounts, but the lye will be correct.

Round off the SoapCalc values to the nearest tenth ounce. For example, 3.118 becomes 3.1, 7.98 becomes 8.0 (not 7.9 like you suggested). You must round the value instead of dropping off digits. Anything 5 or higher becomes the next higher value, anything 4 or lower is discarded.

Have fun going crazy! :)